Boundary design to reduce memory array edge CMP dishing effect

ABSTRACT

In some embodiments, the present disclosure relates to a method of forming an integrated chip. The method includes forming a plurality of memory devices within an embedded memory region of a substrate and forming a plurality of transistor devices within a logic region of the substrate. A first isolation structure is formed within a boundary region of the substrate disposed between the logic region and the embedded memory region. The first isolation structure is formed within a recess in the substrate. A logic wall is formed over the first isolation structure. The logic wall surrounds the embedded memory region and has a first height that is greater than heights of the plurality of memory devices.

REFERENCE TO RELATED APPLICATIONS

This Application is a Divisional of U.S. application Ser. No.16/033,357, filed on Jul. 12, 2018, which claims the benefit of U.S.Provisional Application No. 62/537,131, filed on Jul. 26, 2017. Thecontents of the above-referenced Patent Applications are herebyincorporated by reference in their entirety.

BACKGROUND

Today's electronic devices (e.g., computers, digital cameras, videogames, etc.) commonly contain electronic memory that is used to storedata (e.g., files, pictures, etc.). Electronic memory comes in a varietyof different types. One type of electronic memory that is widely used isflash memory. Flash memory is a non-volatile memory (i.e., a memory thatretains data when not powered) that provides for easy and fast datastorage. Flash memory stores information by trapping charges on a chargetrapping layer in a memory cell. The trapped charges are indicative of adata state stored by the memory cell.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip having an embedded memory region separated from a logicregion by a boundary region.

FIGS. 2A-2D illustrate some embodiments of cross-sectional views of aboundary region arranged between an embedded memory region and a logicregion.

FIG. 3 illustrates some additional embodiments of a cross-sectional viewof a boundary region arranged between an embedded memory region and alogic region.

FIG. 4 illustrates some additional embodiments of a cross-sectional viewof a boundary region arranged between an embedded memory region and alogic region.

FIGS. 5A-5B illustrate some additional embodiments of an integrated chiphaving an embedded memory region separated from a logic region by aboundary region.

FIG. 6 illustrates a cross-sectional view of some additional embodimentsof an integrated chip having an embedded memory region separated from alogic region by a boundary region.

FIG. 7 illustrates a cross-sectional view of some embodiments of amethod of forming an integrated chip, in which a first isolationstructure and a second isolation structure is formed within a substratehaving an embedded memory region separated from a logic region by aboundary region.

FIG. 8A illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a memory wall core andselect gates are formed over the substrate.

FIG. 8B illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a charge trapping layeris formed over the memory wall core and the select gates.

FIG. 8C illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which sidewall spacers areformed along sidewalls of the memory wall and the select gates.

FIG. 9 illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a maximum height of thefirst isolation structure is adjusted.

FIG. 10A illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which transistor gate stacksare formed over the substrate.

FIG. 10B illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which sidewall spacers areformed around the transistor gate stacks.

FIG. 11 illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a contact etch stop layeris formed on the substrate.

FIG. 12 illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a first planarizationprocess is performed.

FIG. 13A illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a gate electrode layer isremoved from the plurality of transistor gate stacks to form gatecavities.

FIG. 13B illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which one or more gate metalsare formed within the gate cavities.

FIG. 14 illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a second planarizationprocess is performed.

FIG. 15 illustrates a cross-sectional view of some embodiments of themethod of forming an integrated chip, in which a silicidation process isperformed.

FIG. 16 illustrates a flow diagram of some embodiments of a method offorming an integrated chip having embedded memory region separated froma logic region by a boundary region.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Many modern day integrated chips comprise embedded memory systems, inwhich logic devices and non-volatile memory (NVM) devices are integratedon a same semiconductor body. The integration of logic and NVM memorydevices onto a same semiconductor body offers improved performance andlower cost over systems having separate chips for memory and logic. Forexample, the integration of logic and NVM devices onto a samesemiconductor body reduces undesirable delays through wires or leadsthat connect two separate chips. Generally, embedded memory systems arefabricated by separately forming NVM devices (e.g., flash memorydevices) and logic devices (e.g., transistors) within different regionsof a semiconductor body.

Sometimes, to further improve performance, embedded memory systems mayuse logic devices comprising high-k metal gate transistors formed by ametal gate replacement process. Within a typical metal gate replacementprocess, dummy gate electrodes are formed over a substrate and adielectric material is formed over and around the dummy gate electrodes.A first planarization process is then performed to expose tops of thedummy gate electrodes followed by an etching process to remove the dummygate electrodes. One or more gate metals are subsequently formed inplace of the removed dummy gate electrodes and a second planarizationprocess is used to remove excess of the gate metals.

Within an embedded memory system, the planarization processes used inthe metal gate replacement process will operate on both the NVM devicesand the transistor devices. It has been appreciated that during theplanarization processes, softer material surrounding an array of the NVMdevices may allow erosion and/or dishing along edges of the array. Theerosion and/or dishing can cause control gates along the edges to havesmaller heights than control gates in a center of the array. Forexample, dishing can cause control gates along the edges to have aheight that is up to approximately 35% smaller than heights of controlgates in the center of the array. When the control gates of the arrayare subsequently silicided to reduce contact resistance, the lowercontrol gate height may lead to full silicidation of the control gatesalong the edges, resulting in increased leakage between the controlgates and the semiconductor body.

The present disclosure, in some embodiments, relates to an integratedchip having an embedded memory region separated from a logic region by aboundary region that is configured reduce erosion and/or dishing alongedges of an embedded memory array, an associated method of fabrication.The integrated chip comprises a logic region having a plurality oftransistor devices and an embedded memory region having a plurality ofmemory devices. A boundary region separates the embedded memory regionfrom the logic region. The boundary region comprises a memory wallsurrounding the embedded memory region and a logic wall surrounding thememory wall. The logic wall has an upper surface that is above thememory wall and the plurality of memory devices. Because the logic wallhas an upper surface that is above the memory wall and the plurality ofmemory devices, the logic wall is able to provide for increasedresistance to erosion and/or dishing along edges of an array of thememory devices.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip 100 having an embedded memory region separated from alogic region by a boundary region.

The integrated chip 100 comprises a substrate 102 including a logicregion 104 separated from an embedded memory region 108 by a boundaryregion 106. The logic region 104 comprises a plurality of transistordevices 110 arranged within the substrate 102 and the embedded memoryregion 108 comprises a plurality of memory devices 124 disposed withinthe substrate 102. In some embodiments, the plurality of transistordevices 110 may comprise high-k metal gate (HKMG) MOSFET transistors. Insome embodiments, the plurality of memory devices 124 may comprisenon-volatile memory (NVM) devices (e.g., flash memory devices). Acontact etch-stop layer (CESL) 126 is over the substrate 102 and aninter-level dielectric (ILD) layer 128 is over the CESL 126. Conductivecontacts 130 are arranged within the ILD layer 128 and one or more metalinterconnect layers 134 are arranged within an inter-metal dielectric(IMD) layer 132 over the ILD layer 128.

The boundary region 106 comprises a wall region 106 a and a dummy region106 b. The wall region 106 a and the dummy region 106 b includeelectrically inactive structures configured to mitigate non-uniformitiesin planarization removal rates (e.g., erosion and/or dishing caused by achemical mechanical planarization process) within the logic region 104and/or within the embedded memory region 108 during manufacture of theintegrated chip 100. The wall region 106 a is disposed between the dummyregion 106 b and the embedded memory region 108. The wall region 106 acomprises a logic wall 116 and a memory wall 118. In some embodiments,the logic wall 116 and the memory wall 118 may be arranged over a firstisolation structure 112 comprising a dielectric material (e.g., anoxide) disposed within the substrate 102. The dummy region 106 b isarranged between the wall region 106 a and the logic region 104 andcomprises a plurality of dummy gate stacks 122 (i.e., a plurality ofelectrically inactive gate stacks). In some embodiments, the pluralityof dummy gate stacks 122 may be arranged over a second isolationstructure 120 separated from the first isolation structure 112 by thesubstrate 102.

The logic wall 116 and the memory wall 118 have sidewalls laterallyseparated from the ILD layer 128 by the CESL 126. The logic wall 116 andthe memory wall 118 also have upper surfaces, facing away from thesubstrate 102, which are completely covered by the ILD layer 128. Insome embodiments, a lower surface of the ILD layer 128 contacting thelogic wall 116 may also contact the CESL 126.

The logic wall 116 is arranged over a first upper surface 112 a of thefirst isolation structure 112 and the memory wall 118 is arranged over asecond upper surface 112 b of the first isolation structure 112. Thefirst upper surface 112 a is disposed along a protrusion 114 extendingout from the second upper surface 112 b. The logic wall 116 has an uppersurface arranged along a horizontal plane 117 that overlies uppersurfaces of plurality of memory devices 124 by a non-zero distance 119.

Because the logic wall 116 has an upper surface that is higher thanupper surfaces of the plurality of memory devices 124, the logic wall116 is able to provide for structure that is able to mitigate erosionand/or dishing (e.g., due to replacement metal gate planarizationprocesses) on the plurality of memory devices 124 along outer edges ofthe embedded memory region 108. By mitigating erosion and/or dishing onthe plurality of memory devices 124 along the outer edge of the embeddedmemory region 108, performance of the memory devices 124 within theembedded memory region 108 is improved. Furthermore, a process window ofthe planarization processes is also improved, thereby reducingprocessing costs associated with the planarization processes.

In some embodiments, the non-zero distance 119 may be in a range ofbetween approximately 25 angstroms and approximately 100 angstroms.Having the non-zero distance 119 be larger than 25 angstroms providesfor improved resistance to dishing from planarization (e.g., CMP)processes, while having the non-zero distance below 100 angstromsretains good planarization of the embedded memory region 106 a. In someembodiments, the horizontal plane 117 may also overlie the memory wall118, the dummy gate stacks 122, and the transistor devices 110. Havingthe horizontal plane 117 also overlie the memory wall 118 and theplurality of dummy gate stacks 122 prevents and/or reducesunder-polishing along peripheries of the embedded memory region 106 aand the logic region 106 b due to the logic wall 116.

FIGS. 2A-2D illustrate cross-sectional views of some embodiments of aboundary region (e.g., 106 of FIG. 1) arranged between an embeddedmemory region (e.g., 108 of FIG. 1) and a logic region (e.g., 104 ofFIG. 1). The embodiments shown in the cross-sectional views of FIGS.2A-2D illustrate some exemplary embodiments of various combinations ofmaterials that may be used in a logic wall (e.g., 116 of FIG. 1) and ina plurality of dummy gate stacks (e.g., 122 of FIG. 1). It will beappreciated that the combinations of materials are not limited to thoseshown in FIGS. 2A-2D.

As shown in cross-sectional view 200 of FIG. 2A, the boundary regioncomprises a first isolation structure 112 and a second isolationstructure 120 laterally separated from the first isolation structure 112by a non-zero distance. A logic wall 116 and a memory wall 118 arearranged over the first isolation structure 112. A plurality of dummygate stacks 122 are arranged over the second isolation structure 120.

The logic wall 116 comprises a logic wall core 210 separated from thefirst isolation structure 112 by a dielectric structure 208 comprisingone or more dielectric materials. The memory wall 118 comprises a memorywall core 212 arranged over the first isolation structure 112. In someembodiments, the memory wall core 212 may directly contact the firstisolation structure 112. The plurality of dummy gate stacks 122respectively comprise a dummy gate 202 separated from the secondisolation structure 120 by a gate dielectric structure 204 comprisingone or more dielectric materials. In some embodiments, the gatedielectric structure 204 and the dielectric structure 208 may comprisestacks of the same dielectric materials.

In some embodiments, the plurality of dummy gates 202 and the logic wallcore 210 may be surrounded by sidewall spacers 206 comprising one ormore dielectric materials. In some embodiments, the sidewall spacers 206may comprise a nitride (e.g., silicon nitride), an oxide (e.g., siliconoxide), or the like. In some embodiments, the memory wall core 212 mayalso be surrounded by sidewall spacers 213 comprising one or moredielectric materials. In some embodiments, sidewall spacers 213 maycomprise the same dielectric materials as sidewall spacers 206. In otherembodiments, sidewall spacers 213 may comprise different dielectricmaterials than sidewall spacers 206. In some embodiments, the pluralityof dummy gates 202 respectively have a first length L₁ between thesidewall spacers 206 and the logic wall core 210 has a second length L₂,larger than the first length L₁, between the sidewall spacers 206. Insome embodiments, the memory wall core 212 may have a third length L₃between the sidewall spacers 213 that is larger than the first lengthL₁. In some embodiments, the third length L₃ may be between the firstlength L₁ and the second length L₂.

In some embodiments, the memory wall core 212 may comprise polysilicon.In various embodiments, the dummy gates 202 and the logic wall core 210may comprise various combinations of one or more conductive materials.For example, in some embodiments shown in cross-sectional view 200 ofFIG. 2A, the dummy gates 202 and the logic wall core 210 may comprisepolysilicon. In such embodiments, the gate dielectric structure 204 andthe dielectric structure 208 may comprise a same material (e.g., anoxide). It has been appreciated that a planarization process used toremove gate metals during a replacement metal gate process may removepolysilicon at a slower rate than the gate metals (e.g., a chemicalmechanical planarization process may remove 50 angstroms of gate metalduring removal of 10 angstroms of polysilicon). Therefore, the use ofpolysilicon within the logic wall core 210 can further reduce dishing ofthe memory devices within an embedded memory region (e.g., 108 of FIG.1).

In other embodiments, shown in cross-sectional view 214 of FIG. 2B, theboundary region may comprise dummy gates 218 and a logic wall core 222comprising one or more gate metals. In such embodiments, the dummy gates218 may be separated from the substrate 102 by a gate dielectricstructure 216 comprising a same material (e.g., a high-k dielectricmaterial) as a dielectric structure 220 separating the logic wall core222 from the substrate 102. In some embodiments, the one or more gatemetals may comprise aluminum, platinum, palladium, nickel, titanium, ora similar metal.

In yet other embodiments, shown in cross-sectional view 224 of FIG. 2C,the boundary region may have dummy gates 202 comprising polysilicon anda logic wall core 222 comprising one or more gate metals. In suchembodiments, the dummy gates 202 may be separated from the substrate 102by a gate dielectric structure 204 comprising a different material thana dielectric structure 220 separating the logic wall core 222 from thesubstrate 102. For example, the gate dielectric structure 204 maycomprise an oxide and/or a nitride and the dielectric structure 220 maycomprise a high-k dielectric material (e.g., hafnium oxide).

In yet other embodiments, shown in cross-sectional view 226 of FIG. 2D,the boundary region may have dummy gates 218 comprising one or more gatemetals and a logic wall core 210 comprising polysilicon. In suchembodiments, the dummy gates 218 may be separated from the substrate 102by a gate dielectric structure 216 comprising a different material thana dielectric structure 208 separating the logic wall core 210 from thesubstrate 102. For example, the gate dielectric structure 216 maycomprise a high-k dielectric material (e.g., hafnium oxide) and thedielectric structure 208 may comprise an oxide and/or a nitride.

FIG. 3 illustrates a cross-sectional view 300 of some additionalembodiments of a disclosed boundary region (e.g., 106 of FIG. 1)arranged between an embedded memory region (e.g., 108 of FIG. 1) and alogic region (e.g., 104 of FIG. 1).

As shown in cross-sectional view 300, the boundary region comprises awall region 106 a and a dummy region 106 b. The wall region 106 acomprises a first isolation structure 112 having a base region 113surrounding by a substrate 102 and an overlying protrusion 114. Theprotrusion 114 directly contacts an upper surface 113 a of the baseregion 113 and has an upper surface that is above the upper surface 113a of the base region 113. In some embodiments, the protrusion 114 iscompletely confined directly above the base region 113. A logic wall 116is arranged over the protrusion 114 and a memory wall 118 is arranged onthe upper surface 113 a of the base region 113 at a position laterallyadjacent to the protrusion 114.

In some embodiments, the base region 113 may comprise a first materialand the protrusion 114 may comprise a second material that is differentthan the first material and/or that has different properties than thefirst material. For example, in some embodiments the first material maycomprise silicon dioxide and the second material may comprise siliconnitride, silicon carbide, or the like. In some embodiments, the baseregion 113 may comprise a low-temperature oxide (LTO) and the protrusion114 may comprise a high temperature oxide (HTO) (e.g., an oxide that isformed using a LPCVD process at a temperature of greater than or equalto approximately 600° C.). The HTO of the protrusion 114 has a higherdensity and a higher dielectric strength than the LTO of the base region113. In other embodiments, the base region 113 may comprise a dielectricmaterial (e.g., silicon dioxide) and the protrusion 114 may comprise asemiconductor (e.g., silicon, polysilicon, germanium, or the like) or ametal (e.g., aluminum, tungsten, titanium, or the like). In yet otherembodiments, the base region 113 and the protrusion 114 may comprise asame material (e.g., silicon dioxide).

The protrusion 114 has a width 302 and a height 304. In someembodiments, a ratio of the width 302 to the height 304 may be in arange of between approximately 20 and approximately 250. For example, insome embodiments, the width 302 may be in a range of betweenapproximately 300 microns and approximately 3,750 microns, and theheight 304 may be in a range of between approximately 150 angstroms andapproximately 500 angstroms.

The height 304 of the protrusion allows the logic wall 116 to have aheight that provides for additional support against CMP dishing withinan embedded memory region (e.g., 108 of FIG. 1), as described above. Ifthe height 304 of the protrusion 114 is less than approximately 150angstroms, the logic wall 116 will fail to provide sufficient supportagainst CMP dishing to avoid damage to the embedded memory region (e.g.,108 of FIG. 1). Alternatively, if the height 304 of the protrusion 114is greater than approximately 400 angstroms, the logic wall 116 willprotrude to a height that negatively effects a planarization of a CMPprocess on the embedded memory region (e.g., resulting in a NVM gateheight that is larger around edges of an NVM array than at a center ofthe NVM array). Furthermore, if the width 302 of the protrusion 114 isless than approximately 300 microns the logic wall 116 will fail toprovide sufficient support against CMP dishing to avoid damage to theembedded memory region (e.g., 108 of FIG. 1), while if the width 302 ofthe protrusion 114 is greater than approximately 3,750 microns theprotrusion 113 will unnecessarily consume costly space on an integratedchip.

The height 304 of the protrusion 114 causes an uppermost surface of thelogic wall 116 to extend above uppermost surfaces of a plurality ofdummy gates 202 by a first distance 306 and above an uppermost surfaceof the memory wall 118 by a second distance 308. In some embodiments,the first distance 306 may be smaller than the second distance 308. Insome embodiments, the first distance 306 may be in a range of betweenapproximately 100 angstroms and approximately 300 angstroms and thesecond distance 308 may be in a range of between approximately 100angstroms and approximately 400 angstroms. In other embodiments, thefirst distance 306 may be in a range of between approximately 150angstroms and approximately 250 angstroms and the second distance 308may be in a range of between approximately 200 angstroms andapproximately 300 angstroms. In some embodiments, logic wall 116 and thememory wall 118 may have heights that are approximately the same (e.g.,between approximately 600 angstroms and approximately 700 angstroms),such that the second distance 308 may be approximately equal to theheight 304. Having the second distance 308 in the range of betweenapproximately 100 angstroms and approximately 400 angstroms provides forsupport against CMP dishing without resulting in a NVM gate height thatis larger around edges of an NVM array than in a center of the NVMarray.

In some embodiments, the protrusion 114 has an outermost sidewall thatmay be laterally offset from an outermost sidewall of the base region113 by a first distance 310. In some embodiments, the first distance 310may be in a range of between approximately 0 nm and approximately 150nm. In other embodiments, the first distance 310 may be in a range ofbetween approximately 50 nm and approximately 100 nm. In someembodiments, an outermost sidewall of the logic wall 116 may laterallyoffset from the outermost sidewall of the protrusion 114 by a seconddistance 312. In various embodiments, the second distance 312 may be ina range of between approximately 100 nm and approximately 200 nm. Thefirst distance 310 and/or the second distance 312 account formisalignment errors and keep the protrusion 114 and/or the logic wall116 directly over the base region 113, thereby enabling the formation ofconductive contacts at locations neighboring the first isolationstructure 112 (e.g., to enable conductive contact 130 to reach contactregion 544, as shown in FIG. 5A).

FIG. 4 illustrates a cross-sectional view 400 of some additionalembodiments of a disclosed boundary region (e.g., 106 of FIG. 1)arranged between an embedded memory region (e.g., 108 of FIG. 1) and alogic region (e.g., 104 of FIG. 1).

As shown in cross-sectional view 400, the boundary region 106 comprisesa wall region 106 a and a dummy region 106 b. The wall region 106 acomprises a first isolation structure 112 having a base region 113surrounding by a substrate 102 and an overlying protrusion 114 disposedon the base region 113. In some embodiments, sidewalls of the protrusion114 may be angled at an angle that is between 0° and 90° as measuredwith respect to a line that is normal to the upper surface 113 a of thebase region 113. In other embodiments, the sidewalls of the protrusion114 may be angled at an angle that is between 5° and 85° as measuredwith respect to the line that is normal to the upper surface 113 a ofthe base region 113.

In some embodiments, the base region 113 may have one or more surfacesdefining a first divot 402 recessed below the upper 113 a surface of thebase region 113. The first divot 402 may be arranged along an edge ofthe base region 113. In some embodiments, the protrusion 114 comprisesone or more dielectric materials that extend to within the first divot402. In some embodiments, the protrusion 114 may have one or moresurfaces defining a second divot 404 that is arranged along an uppersurface of the protrusion 114. In some embodiments, the second divot 404may be arranged directly over the first divot 302. In other embodiments,the second divot 404 may be arranged laterally between the first divot402 and the logic wall 116. In yet other embodiments, the second divot404 may be arranged between a first upper surface of the protrusion 114and a second upper surface of the protrusion 114 that is higher than thefirst upper surface. In some embodiments, the first divot may have afirst depth 406 that is greater than a second depth 408 of the seconddivot 404.

FIGS. 5A-5B illustrate some additional embodiments of an integrated chiphaving an embedded memory region separated from a logic region by aboundary region.

As shown in cross-sectional view 500 of FIG. 5A, the integrated chipcomprises a substrate 102 having a logic region 104, an embedded memoryregion 108, and a boundary region 106 separating the logic region 104from the embedded memory region 108. In various embodiments, thesubstrate 102 may comprise a semiconductor material such as silicon,germanium, or the like. In some embodiments, the substrate 102 maycomprise an SOI (silicon-on-insulator) substrate.

The logic region 104 comprises a plurality of transistor devices. Insome embodiments, the transistors devices may be high-k metal gate(HKMG) transistors, 502 a and 502 b. The HKMG transistors, 502 a and 502b, respectively comprise metal gate electrodes, 504 a and 504 b,separated from the substrate 102 by one or more dielectric layers506-510. Source/drain regions 518 are arranged on opposing sides of themetal gate electrodes, 504 a and 504 b. Sidewall spacers 206 extendalong outer sidewalls of the metal gate electrodes, 504 a and 504 b. Insome embodiments, the sidewall spacer 206 may comprise a plurality ofspacer layers 512-516 comprising different dielectric materials. Forexample, the sidewall spacers 206 may comprise a first spacer layer 512comprising a first oxide, a second spacer layer 514 comprising anitride, and a third spacer layer 516 comprising a second oxide.

In some embodiments, metal gate electrode 504 a may comprise a p-typemetal (e.g., ruthenium, palladium, or the like) and metal gate electrode504 b may comprise an n-type metal (e.g., hafnium, zirconium, titanium,or the like). In some embodiments, the one or more dielectric layers506-510 comprise a high-k dielectric layer 508 over a base dielectriclayer 506 (e.g., an oxide). In some additional embodiments, the one ormore dielectric layers 506-510 may further comprise an etch-stop layer510 over the high-k dielectric layer 508. In some embodiments, thesource/drain regions 518 may comprise highly doped regions of thesubstrate 102. In other embodiments, the source/drain regions 518 maycomprise epitaxial source/drain regions comprising a semiconductormaterial disposed within recesses within the substrate 102 (e.g.,silicon germanium disposed within recesses within a silicon substrate).

The embedded memory region 108 comprises a plurality of split-gate flashmemory cells, 520 a and 520 b. The split-gate flash memory cells, 520 aand 520 b, respectively comprise a select gate 522 and a control gate524 separated by a charge trapping layer 526. In some embodiments, theselect gate 522 may be separated from the substrate 102 by a gatedielectric 528 (e.g., an oxide, a nitride, or the like). Source/drainregions 532 are arranged along opposing sides of the split-gate flashmemory cells, 520 a and 520 b. In some embodiments, a silicide layer 534is disposed on upper surfaces of the select gate 522 and the controlgate 524.

In some embodiments, the select gate 522 and the control gate 524 maycomprise polysilicon. In some embodiments, the charge trapping layer 526includes a charge trapping nitride layer sandwiched between two oxidelayers. In other embodiments, the charge trapping layer 526 may includea layer of silicon nanoparticle dots. In some embodiments, sidewallspacers 530 are disposed along outer sidewalls of the select gate 522and the control gate 524. In some embodiments, sidewall spacers 530 maybe the same (e.g., comprise a same stack of dielectric materials in asame order) as sidewall spacers 206.

Conductive contacts 130 are surrounded by an ILD layer 128 and extendfrom the silicide layer 534 to overlying metal interconnect layers (notshown). The silicide layer 534 is configured to reduce contactresistance of the conductive contacts 130. In some embodiments, the ILDlayer 128 may comprise an oxide, a low-k dielectric material, or anultra low-k dielectric material. For example, in some embodiments, theILD layer 128 may comprise borophosphosilicate glass (BPSG),borosilicate glass (BSG), and phosphosilicate glass (PSG), or the like.In some embodiments, a contact etch-stop layer (CESL) 126 is between thesubstrate 102 and the ILD layer 128.

The boundary region 106 comprises a wall region 106 a and a dummy region106 b. The dummy region 106 b is arranged between the wall region 106 aand the logic region 104 and comprises a plurality of dummy gate stacks122 (i.e., a plurality of electrically inactive gate stacks). In variousembodiments, the plurality of dummy gate stacks 122 may comprise a dummygate electrode 536 including polysilicon or one or more gate metals. Thewall region 106 a comprises a logic wall 116 and a memory wall 118. Invarious embodiments, the logic wall 116 may comprise a logic wall core538 including polysilicon or one or more gate metals. In someembodiments, the memory wall 118 may comprise a memory wall core 540including polysilicon or one or more gate metals. In some embodiments,the memory wall core 540 may be a same material (e.g., polysilicon) asthe select gate 522 and/or the control gate 524.

In some embodiments, the logic wall 116 and a memory wall 118 may bearranged over a first isolation structure 112 comprising a dielectricmaterial (e.g., an oxide) disposed within the substrate 102. The firstisolation structure 112 has a protrusion 114 with a first upper surface112 a. The protrusion 114 protrudes outward from a second upper surface112 b of the first isolation structure 112. In some embodiments, thelogic wall 116 is arranged over the first upper surface 112 a and thememory wall 118 is arranged over the second upper surface 112 b. In someembodiments, the plurality of dummy gate stacks 122 may be arranged overa second isolation structure 120 separated from the first isolationstructure 112 by the substrate 102.

In some embodiments, the plurality of memory devices, 520 a and 520 b,may be arranged within a well region 542 within the substrate 102 (e.g.,an n-well within a p-type substrate). The well region 542 may extend toa position that is between the first isolation structure 112 and thesecond isolation structure 120. In such embodiments, a conductivecontact 130 may extend though the ILD layer 128 to a pickup regioncomprising a contact region 544 (e.g., an n+ region) within the wellregion 542. The conductive contact 130 enables a bias to be applied tothe well region 542 to provide for isolation and changes in theoperation of the plurality of split-gate flash memory cells, 520 a and520 b. In some embodiments, an upper surface of the substrate 102 isrecessed between the first isolation structure 112 and the secondisolation structure 120.

FIG. 5B illustrates a top-view 546 of the integrated chip shown incross-sectional view 500. As shown in top-view 546, the memory wall 118is arranged over the first isolation structure 112 and continuouslyextends as an unbroken structure around the memory region 108 comprisingthe plurality of split gate flash memory cells (e.g., 520 a and 520 b ofFIG. 5A). The logic wall 116 is arranged over the first isolationstructure 112 and is separated from the memory wall 118. The logic wall116 continuously extends around the memory wall 118 as an unbrokenstructure. A plurality of dummy gate stacks 122 are arranged over thesecond isolation structure 120 and surround the logic wall 116. Thefirst isolation structure 112 and the second isolation structure 120 areseparated by the pickup region.

Although FIGS. 5A-5B illustrate an embedded memory region having splitgate flash memory cells, it will be appreciated that the disclosedboundary region is not limited to use with such memory cell structures.Rather, the disclosed boundary region is not limited to use withembedded memory regions having memory cells with varying structures. Forexample, FIG. 6 illustrates a cross-sectional view of some alternativeembodiments of an integrated chip 600 having an embedded memory regionseparated from a logic region by a boundary region.

The integrated chip 600 comprises a substrate 102 having a logic region104, an embedded memory region 108, and a boundary region 106. Theembedded memory region 108 comprises a pair of flash memory cells, 602 aand 602 b, comprising a common source region 614 located between a firstdrain region 616 a and a second drain region 616 b. The common sourceregion 614, the first drain region 616 a, and the second drain region616 b are disposed along a top surface of the substrate 102. A firstchannel region extends between the common source region 614 and thefirst drain region 616 a, and a second channel region extends betweenthe common source region 614 and the second drain region 616 b.

The flash memory cells, 602 a and 602 b, further comprise a dielectriclayer 604 disposed over a substrate 102. Floating gates, 606 a and 606b, are located over the dielectric layer 604. The floating gates, 606 aand 606 b, may comprise polysilicon, metal, metal silicide, metalnitride, or dielectric having a high trapping density, such as siliconnitride. Control gates, 608 a and 608 b, are disposed over the floatinggates, 606 a and 606 b, while select gates, 610 a and 610 b, aredisposed next to the floating gate, 606 a and 606 b, respectively. Thecontrol gates, 608 a and 608 b, and the select gates, 610 a and 610 b,are configured to control a data state stored in an adjacent floatinggate, 606 a and 606 b. An erase gate 612 is arranged between thefloating gates 606 a and 606 b, and over the common source region 614.

In some embodiments, an additional dielectric material 618 is disposedover the substrate 102 between the control gates, 608 a and 608 b, theselect gates, 610 a and 610 b, the common erase gate 612, and thefloating gates, 606 a and 606 b. In some embodiments, a protectivecoating 620 may be disposed over the additional dielectric material 618.The protective coating 620 may comprise a dielectric layer, such assilicon oxide, silicon nitride or a combination thereof.

FIGS. 7-15 illustrate cross-sectional views 700-1500 of some embodimentsof a method of forming an integrated chip having an embedded memoryregion separated from a logic region by a boundary region. Although thecross-sectional views 700-1500 shown in FIGS. 7-15 are described withreference to a method, it will be appreciated that the structures shownin FIGS. 7-15 are not limited to the method but rather may stand aloneseparate of the method.

As shown in cross-sectional view 700 of FIG. 7, a substrate 102 isprovided. In various embodiments, the substrate 102 may be any type ofsemiconductor body (e.g., silicon, SiGe, SOI, etc.), as well as anyother type of semiconductor, epitaxial, dielectric, or metal layers,associated therewith. The substrate 102 comprises a logic region 104separated from an embedded memory region 108 by way of a boundary region106.

A base region 113 of a first isolation structure 112 and a secondisolation structure 120 are formed within the boundary region 106 of thesubstrate 102. In some embodiments, the base region 113 of the firstisolation structure 112 and the second isolation structure 120 may beformed by selectively etching the substrate 102 to form recesses definedby interior surfaces of the substrate 102. A dielectric material (e.g.,an oxide, a nitride, or the like) is subsequently formed within therecesses. In some embodiments, the dielectric material may be formed byway of a deposition technique (e.g., physical vapor deposition (PVD),chemical vapor deposition (CVD), PE-CVD, atomic layer deposition (ALD),sputtering, etc.). In other embodiments, the dielectric material may beformed by way of low temperature oxidation process (e.g., an oxidationprocess performed at a temperature of less than or equal toapproximately 500° C.). In some embodiments, the base region 113 of thefirst isolation structure 112 and the second isolation structure 120protrude outward from surrounding surfaces of the substrate 102 by anon-zero distance.

As shown in cross-sectional view 800 of FIGS. 8A-8C, a plurality ofmemory device structures (810 a-810 b of FIG. 8C) are formed within theembedded memory region 108 and a memory wall (804 of FIG. 8C) is formedover the base region 113 of the first isolation structure 112 within theboundary region 106. In some embodiments, the plurality of memory devicestructures (810 a-810 b of FIG. 8C) may correspond to non-volatilememory (NVM) devices (e.g., flash memory devices). The memory wall (804of FIG. 8C) may be formed concurrent to the formation of the pluralityof memory device structures 810 a-810 b of FIG. 8C).

As shown in cross-sectional view 800 of FIG. 8A, a gate dielectric layeris formed over the substrate 102. In some embodiments, the gatedielectric layer may comprise an oxide (e.g., SiO₂) formed by way of athermal process. In alternative embodiments, the gate dielectric layermay be formed by a deposition process (e.g., chemical vapor deposition(CVD), physical vapor deposition (PVD), atomic layer deposition (ALD),etc.). A select gate layer is formed over the gate dielectric layer andthe base region 113 of the first isolation structure 112, and a firsthard mask layer 802 is selectively formed over the select gate layer.The select gate layer and the gate dielectric layer are then etchedaccording to the first hard mask layer 802 to define select gates 522over a gate dielectric 528 and a memory wall 804 having a memory wallcore 540 over the base region 113 of the first isolation structure 112.In some embodiments, an upper surface of the first hard mask layer 802over the memory wall core 540 is vertically offset from upper surfacesof the first hard mask layer 802 over the select gates 522 by a non-zerodistance 803.

As shown in cross-sectional view 806 of FIG. 8B, a charge trapping layeris formed over the memory wall core 540 and the select gates 522, and acontrol gate layer is formed over the charge trapping layer within theembedded memory region 108. A second hard mask layer 808 is selectivelyformed over the control gate layer. The control gate layer and thecharge trapping layer are then etched according to the second hard masklayer 808 to define a control gate 524 and a charge trapping layer 526within the plurality of memory device structures 810 a-810 b. In someembodiments, the select gate layer and a control gate layer may comprisedoped polysilicon formed by deposition processes (e.g., CVD, PVD, ALD,etc.). In some embodiments, the first hard mask layer 802 and the secondhard mask layer 808 may comprise an oxide (e.g., PE-SiON), a nitride(e.g., silicon nitride (SiN), a carbide (e.g., SiC), or the like.

As shown in cross-sectional view 812 of FIG. 8C, sidewall spacers 530are formed along sidewalls of the memory wall 804 and the memory devicestructures 810 a-810 b. In some embodiments, the sidewall spacers 530may be formed by depositing one or more spacer layers over the substrate102 using a deposition technique (e.g., PVD, CVD, PE-CVD, ALD,sputtering, etc.). In various embodiments, the one or more spacer layersmay comprise silicon nitride, a silicon dioxide (SiO₂), siliconoxy-nitride (e.g., SiON), or a similar material. The one or more spacerlayers are subsequently etched to remove the one or more spacer layersfrom horizontal surfaces, leaving sidewall spacers 530 along opposingsides of the memory wall 804 and the memory device structures 810 a-810b.

Source/drain regions 532 are formed within the embedded memory region108. In some embodiments, the source/drain regions 532 may be formed byselectively implanting a dopant species into the substrate 102. In someembodiments, the dopant species may be selectively implanted into thesubstrate 102 according to a mask comprising the memory devicestructures 810 a-810 b. In various embodiments, the dopant species maycomprise a p-type dopant (e.g., boron, gallium, etc.) or an n-typedopant (e.g., phosphorus, arsenic, etc.). In some embodiments, afterimplanting the dopant species into the substrate 102, a drive-in annealmay be performed to diffuse the dopant species within the substrate 102.

As shown in cross-sectional view 900 of FIG. 9, a maximum height of thefirst isolation structure 112 is adjusted. In some embodiments, themaximum height may be adjusted by forming a protrusion 114 protrudingoutward from an upper surface of the base region 113 of the firstisolation structure 112. In some embodiments, the protrusion 114 may beformed using a high-temperature oxide (HTO) process to increase a height(e.g., by between 100 angstroms and 300 angstroms) of a part of thefirst isolation structure 112. For example, in some embodiments, amasking layer 902 may be formed over the logic region 104 and theembedded memory region 108 and a thermal oxidation process may besubsequently formed. In other embodiments, the protrusion 114 may beformed using a deposition process followed by an etching process.

In some embodiments, the protrusion 114 may be formed to comprise ahigh-temperature oxide (HTO) (e.g., an oxide that is formed at atemperature of greater than or equal to approximately 600° C.). In somesuch embodiments, the protrusion 114 may be formed using a low pressurechemical vapor deposition (LPCVD) process. In some embodiments, theLPCVD process may performed at a pressure that is in a range of betweenapproximately 10 mT (milli-Torr) and approximately 1000 mT. In otherembodiments, the LPCVD process may performed at other pressures. In someembodiments, the LPCVD process used to form the HTO may performed at atemperature that is in a range of between approximately 800° C. andapproximately 1,300° C. In some embodiments, the HTO may comprisesilicon dioxide formed by reacting dichlorosilane (SiH₂Cl₂) and nitrousoxide (2N₂O) within a processing chamber (e.g., SiH₂Cl₂+2N₂O→SiO₂+₂N₂+2HCl).

As shown in cross-sectional views 1000 and 1014 of FIGS. 10A-10B, aplurality of transistor gate stacks 1008 a-1008 b are formed within thelogic region 104. Within the boundary region 106, a plurality of dummygate stacks 1010 a-1010 b are formed over the second isolation structure120 and a logic wall 1012 is formed over the protrusion 114. In someembodiments, the plurality of transistor gate stacks 1008 a-1008 b, theplurality of dummy gate stacks 1010 a-1010 b, and the logic wall 1012may be formed with an embedded memory cap 1002 covering the plurality ofmemory device structure 810 a-810 b and the memory wall 804. In someembodiments, the plurality of transistor gate stacks 1008 a-1008 b, theplurality of dummy gate stacks 1010 a-1010 b, and the logic wall 1012may be concurrently formed.

As shown in cross-sectional view 1000 of FIG. 10A, one or more gatedielectric layers are formed over the substrate 102. A gate electrodelayer is formed over the one or more gate dielectric layers. The one ormore gate dielectric layers and the gate electrode layer are selectivelypatterned to define the plurality of transistor gate stacks 1008 a-1008b, the plurality of dummy gate stacks 1010 a-1010 b, and the logic wall1012, respectively comprising a gate electrode layer 1004 arranged overgate dielectrics 508-510. The logic wall 1012 has an upper surface thatoverlies upper surfaces of the memory wall 804 and the memory devicestructures 810 a-810 b. In various embodiments, the gate electrode layer1004 within the plurality of transistor gate stacks 1008 a-1008 b, theplurality of dummy gate stacks 1010 a-1010 b, and/or the logic wall 1012may comprise a sacrificial gate electrode layer that is subsequentlyremoved during a metal gate replacement process (e.g., shown in FIGS.13A-13B).

In some embodiments, prior to the etching process a hard mask layer 1006may be selectively formed over the gate electrode layer 1004 and the oneor more gate dielectric layers. The hard mask layer 1006 is subsequentlyused as a mask for the etching process. In some embodiments, the gateelectrode layer may comprise polysilicon. In some embodiments, the oneor more gate dielectric layers may comprise an oxide (e.g., siliconoxide), a nitride (e.g., silicon oxy-nitride), or the like. In otherembodiments, the one or more gate dielectric layers may comprise ahigh-k dielectric material, such as hafnium oxide (HfO₂), TiO₂, HfZrO,Ta₂O₃, HfSiO₄, ZrO₂, ZrSiO₂, or the like.

As shown in cross-sectional view 1014 of FIG. 10B, sidewall spacers 206are formed along opposing sides of the plurality of transistor gatestacks 1008 a-1008 b, the plurality of dummy gate stacks 1010 a-1010 b,and the logic wall 1012. In various embodiments, the sidewall spacers206 may comprise silicon nitride, silicon dioxide, silicon oxy-nitride,or a similar material. In some embodiments, the sidewall spacers 206 maybe formed by depositing one or more spacer layers 512-516 over thesubstrate 102. In some embodiments, the one or more spacer layers512-516 are deposited over the substrate 102 using a depositiontechnique (e.g., PVD, CVD, PE-CVD, ALD, sputtering, etc.). In someembodiments, the one or more spacer layers 512-516 may comprise a firstspacer layer 512 comprising an oxide, a second spacer layer 514comprising a nitride, and a third spacer layer 516 comprising an oxide.The one or more spacer layers 512-516 are subsequently etched to removethe one or more spacer layers 512-516 from horizontal surfaces.

Source/drain regions 518 are formed within the logic region 104. In someembodiments, the source/drain regions 518 may be formed by selectivelyimplanting a dopant species into the substrate 102 according to a maskcomprising the plurality of transistor gate stacks 1008 a-1008 b, theplurality of dummy gate stacks 1010 a-1010 b, the logic wall 1012, andthe sidewall spacers 206.

In some alternative embodiments (not shown), the sidewall spacers 206and 530 may be concurrently formed after formation of the plurality oftransistor gate stacks 1008 a-1008 b, the plurality of dummy gate stacks1010 a-1010 b, and the logic wall 1012. In such embodiments, theembedded memory cap 1002 may be removed after formation of the pluralityof transistor gate stacks 1008 a-1008 b, the plurality of dummy gatestacks 1010 a-1010 b, and the logic wall 1012. One or more spacer layersare subsequently formed in the logic region 104, the boundary region106, and the embedded memory region 108. The one or more spacer layersare then etched to concurrently form sidewall spacers 206 and 530 byremoving the one or more spacer layers 512-516 from horizontal surfaces.

As shown in cross-sectional view 1100 of FIG. 11, a contact etch stoplayer (CESL) 126 is formed on to the substrate 102. The CESL 126 may beformed by a deposition process (e.g., CVD, PVD, PE-CVD, etc.) andcomprise a nitride layer (e.g., silicon nitride), a carbide layer (e.g.,silicon carbide), or the like. A first inter-level dielectric (ILD)layer 1102 is formed onto the substrate 102 at a position above the CESL126. In some embodiments the ILD layer 1102 may comprise an oxide, alow-k dielectric material, or an ultra low-k dielectric material.

As shown in cross-sectional view 1200 of FIG. 12, a first planarizationprocess 1201 is performed. The first planarization process 1201 removesa part of the CESL 126 and the first ILD layer 1102 to form a pluralityof transistor gate stacks 1202 a-1202 b, a plurality of dummy gatestacks 122, and a logic wall 116. In some embodiments, the firstplanarization process 1201 may comprise a chemical mechanicalplanarization (CMP) process. The first planarization process 1201removes parts of the CESL 126, the first ILD layer 902, and the hardmask layer (1006 of FIG. 11) down to and exposing the polysilicon gate.In some embodiments, the first planarization process 1201 may alsoremove the first hard mask layer (802 of FIG. 11) and the second hardmask layer (808 of FIG. 11) to define a memory wall 118 and a pluralityof memory devices 520 a-520 b. In other embodiments, first hard masklayer (802 of FIG. 11) and the second hard mask layer (808 of FIG. 11)may be removed prior to the first planarization process.

It has been appreciated that the removal rate of a CMP process is basedupon such factors as pressure, temperature, and speed of the CMPprocess. It has also been appreciated that the removal rate of the CMPprocess is different for different materials (resulting in localnon-planarities over the substrate). Because the first elevation of thelogic wall 116 is higher than the elevations of the plurality of memorydevices 520 a-520 b and the memory wall 118, the logic wall 116 limitspressures that the first planarization process 1201 applies to thememory wall 118 and along edges of the embedded memory region 108. Thelimited pressure will reduce a removal rate of the memory wall 118 andthe plurality of memory devices 520 a-520 b along edges of the embeddedmemory region 108 and therefore will mitigate dishing along the edges.

As shown in cross-sectional views, 1300 and 1306, of FIGS. 13A-13B, areplacement metal gate process is performed on transistors within thelogic region.

As shown in cross-sectional view 1300 of FIG. 13A, the replacement metalgate process removes the gate electrode layer from the plurality oftransistor gate stacks 1202 a-1202. Removing the dummy gates electrodesresults in gate cavities 1302 a-1302 b arranged between sidewallspacers. In some embodiments, the gate electrode layer may be removed byan etching process 1304. For example, in some embodiments (not shown) amasking layer (e.g., photoresist) may be selectively formed over thesubstrate 102 and a subsequent etching process 1304 may be performed toremove the gate electrode layer. In some additional embodiments (notshown), the etching process 1304 may also remove the gate electrodematerial from within the dummy gate stacks 122 and/or within the logicwall 116.

As shown in cross-sectional view 1306 of FIG. 13B, one or more gatemetals 1308 are formed within the gate cavities 1302 a-1302 b and overthe first ILD layer 1102. In various embodiments, the one or more gatemetals may be formed by way of deposition processes (e.g., PVD, CVE,PE-CVD, etc.). In some additional embodiments (not shown), the one ormore gate metals 1308 may be formed within the dummy gate stacks and/orwithin the logic wall. In some embodiments, the one or more gate metals1308 may comprise an n-type metal such as may comprise aluminum,tantalum, titanium, or the like. In some embodiments, the one or moregate metals 1308 may comprise a p-type metal, such as platinum,tungsten, nickel, or the like. In some embodiments, the dielectric layermay also be removed and replaced with a high-k gate dielectric. In otherembodiments, wherein the dielectric layer 508 comprises a high-kdielectric layer, the dielectric layer may not be removed.

As shown in cross-sectional view 1400 of FIG. 14, a second planarizationprocess 1401 is performed to remove excess of the one or more gatemetals 1308. Removing excess of the one or more gate metals 1308 resultsin high-k metal gate (HKMG) transistors, 502 a and 502 b. The HKMGtransistors, 502 a and 502 b, respectively comprise metal gateelectrodes, 504 a and 504 b, separated from the substrate 102 by one ormore dielectric layers 508-510. In some embodiments, the secondplanarization process 1401 may comprise a CMP process. Because the firstelevation of the logic wall 116 is higher than the elevations of theplurality of memory devices 520 a-520 b and the memory wall 118, thelogic wall 116 limits pressures that the second planarization process1401 applies to the memory wall 118 and along edges of the embeddedmemory region 108. The limited pressure will reduce a removal rate ofthe memory wall 118 and the plurality of memory devices 520 a-520 balong edges of the embedded memory region 108 and therefore willmitigate dishing along the edges.

As shown in cross-sectional view 1500 of FIG. 15, a silicidation processis performed to form a silicide layer 534 along upper surfaces of thecontrol gate 524 and the select gate 522 within the memory devices 520a-520 b. In some embodiments, the silicidation process may be performedby depositing a metal layer (e.g., a nickel layer) and then performing athermal annealing process (e.g., a rapid thermal anneal) to form asilicide layer 534.

Conductive contacts 130 are formed within a second ILD layer 1502 overthe first ILD layer 1102. The conductive contacts 130 extend through thesecond ILD layer 1502 to contact the silicide layers 534 and the metalgate electrodes, 504 a and 504 b. In some embodiments, the conductivecontacts 130 may be formed by way of a damascene process. In suchembodiments, the second ILD layer 1502 is formed over the first ILDlayer 1102. The second ILD layer 1502 is etched to form contact holes,and the contact holes are subsequently filled with a conductive material(e.g., copper and/or aluminum). A chemical mechanical planarization(CMP) process is subsequently performed to remove excess of theconductive material from over the second ILD layer 1502.

FIG. 16 illustrates a flow diagram of some embodiments of a method 1600of forming an integrated chip having an embedded memory region separatedfrom a logic region by a boundary region.

While method 1600 is illustrated and described herein as a series ofacts or events, it will be appreciated that the illustrated ordering ofsuch acts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At 1602, a base region of a first isolation structure and a secondisolation structure are formed within a boundary region of a substrate.FIG. 7 illustrates a cross-sectional view 700 of some embodimentscorresponding to act 1602.

At 1604, a plurality of memory device structures are formed within anembedded memory region of substrate. In some embodiments, the pluralityof memory devices may comprise non-volatile memory (NVM) devices. FIGS.8A-8C illustrate cross-sectional views of some embodiments correspondingto act 1604.

At 1606, a memory wall surrounding the plurality of memory devicestructures is formed over the base region 113 of the first isolationstructure. FIGS. 8A-8C illustrate cross-sectional views of someembodiments corresponding to act 1606.

At 1608, an embedded memory cap is formed over the plurality of memorydevice structures and the memory wall. FIGS. 8A-8C illustratecross-sectional views of some embodiments corresponding to act 1608.

At 1610, a height of a part of the first isolation structure is adjustedby forming a protrusion protruding outward from an upper surface of thefirst isolation structure. In some embodiments, the height may beadjusted by performing a high-temperature oxide (HTO) process toincrease a height (e.g., between 100 angstroms and 200 angstroms) of apart of the first isolation structure. FIG. 9 illustrates across-sectional view 900 of some embodiments corresponding to act 1610.

At 1612, a plurality of transistor device stacks are formed within logicregion of substrate that is separated from memory region by the boundaryregion. In some embodiments, the plurality of transistor device stacksmay comprise sacrificial gate structures. FIGS. 10A-10B illustratecross-sectional views of some embodiments corresponding to act 1612.

At 1614, a plurality of dummy gate stacks are formed over the secondisolation structure within the boundary region. FIGS. 10A-10B illustratecross-sectional views of some embodiments corresponding to act 1614.

At 1616, a logic wall is formed over the protrusion. FIGS. 10A-10Billustrate cross-sectional views of some embodiments corresponding toact 1616.

At 1618, the embedded memory cap is removed from over the plurality ofmemory device structures and the memory wall.

At 1620, a contact etch stop layer (CESL) is formed over substrate. FIG.11 illustrates a cross-sectional view 1100 of some embodimentscorresponding to act 1620.

At 1622, a first planarization process is performed to remove part ofthe CESL and expose the sacrificial gate structures. FIG. 12 illustratesa cross-sectional view 1200 of some embodiments corresponding to act1622.

At 1624, a replacement metal gate process is performed on the pluralityof transistor device stacks. The replacement metal gate process removesthe sacrificial gate electrodes from the plurality of transistor devicestacks and forms ones or more gate metals within locations of theremoved sacrificial gate electrodes. FIGS. 13A-13B illustratescross-sectional views of some embodiments corresponding to act 1624.

At 1626, a second planarization process is performed to remove excess ofthe ones or more gate metals. FIG. 14 illustrates a cross-sectional view1400 of some embodiments corresponding to act 1626.

At 1628, a silicidation process is performed. FIG. 15 illustrates across-sectional view 1500 of some embodiments corresponding to act 1628.

At 1630, conductive contacts are formed within an ILD layer over thesubstrate. FIG. 15 illustrates a cross-sectional view 1500 of someembodiments corresponding to act 1630.

Accordingly, in some embodiments, the present disclosure relates to anintegrated chip having an embedded memory region separated from a logicregion by a boundary region that is configured reduce erosion and/ordishing along edges of an embedded memory array, an associated method offabrication.

In some embodiments, the present disclosure relates to an integratedchip. The integrated chip includes a logic region having a plurality oftransistor devices disposed within a substrate; an embedded memoryregion having a plurality of memory devices disposed within thesubstrate; a boundary region separating the logic region from theembedded memory region, the boundary region includes a first isolationstructure having a first upper surface and a second upper surface belowthe first upper surface, the first upper surface is coupled to thesecond upper surface by way of a sidewall overlying the first isolationstructure; a memory wall arranged on the second upper surface andsurrounding the embedded memory region; and a logic wall arranged on thefirst upper surface and surrounding the memory wall, the logic wallhaving an upper surface that is above the plurality of memory devicesand the memory wall. In some embodiments, the plurality of memorydevices include flash memory devices having a control gate separatedfrom a select gate by a charge trapping dielectric layer; and the memorywall includes a same material as the control gate or the select gate. Insome embodiments, the interior sidewall is oriented at a non-zero anglewith respect to a line normal to the second upper surface. In someembodiments, the first upper surface is disposed along a horizontalplane that overlies the second upper surface. In some embodiments, theintegrated chip further includes a second isolation structure having asecond dielectric material disposed within the substrate in the boundaryregion between the first isolation structure and the logic region; and aplurality of dummy gate stacks arranged over the second isolationstructure. In some embodiments, the plurality of dummy gate stacks haveupper surfaces that are below the upper surface of the logic wall. Insome embodiments, an uppermost surface of the second isolation structureis arranged below the first upper surface of the first isolationstructure. In some embodiments, the first isolation structure and thesecond isolation structure protrude outward from a surface of thesubstrate located between the first isolation structure and the secondisolation structure. In some embodiments, the logic wall and theplurality of dummy gate stacks comprise polysilicon. In someembodiments, the logic wall comprises polysilicon and the plurality ofdummy gate stacks comprise one or more gate metals. In some embodiments,the integrated chip further includes a contact etch stop layer arrangedover the substrate; and an inter-level dielectric (ILD) layer laterallyseparated from the memory wall and the logic wall by the contact etchstop layer.

In other embodiments, the present disclosure relates to an integratedchip. The integrated chip includes a plurality of transistor devicesdisposed within a logic region of a substrate; a plurality of memorydevices disposed within an embedded memory region of the substrate; afirst isolation structure having a first dielectric material disposedwithin the substrate between the plurality of transistor devices and theplurality of memory devices; a second isolation structure having asecond dielectric material disposed within the substrate between thefirst isolation structure and the plurality of transistor devices; aplurality of dummy gate stacks arranged over the second isolationstructure; a memory wall continuously arranged over a lower surface ofthe first isolation structure and extending as a first unbrokenstructure around the plurality of memory devices; and a logic wallarranged over a higher surface of the first isolation structure andcontinuously extending as a second unbroken structure around the memorywall, the logic wall having an uppermost surface arranged along ahorizontal plane that is separated from the memory wall and theplurality of dummy gate stacks by non-zero distances. In someembodiments, the first isolation structure has a base region and aprotrusion that extends outward from an upper surface of the base regionand that is completely confined above the base region, the memory wallcontacts the base region and the logic wall contacts the protrusion. Insome embodiments, the base region includes a first material and theprotrusion includes a second material that is different than the firstmaterial. In some embodiments, the protrusion has a height and a widththat is in a range of between approximately 20 and approximately 250times larger than the height. In some embodiments, the protrusion has anoutermost sidewall that is laterally offset from an outermost sidewallof the base region by a non-zero distance. In some embodiments, the baseregion has one or more surfaces defining a divot recessed below theupper surface of the base region, and the protrusion includes one ormore dielectric materials that extend to within the divot. In someembodiments, the uppermost surface extends past opposing sidewalls ofthe logic wall.

In yet other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming a plurality oftransistor devices within a logic region of a substrate; forming aplurality of memory devices within an embedded memory region of thesubstrate; forming a first dielectric within a recess in the substrateto form a base region of a first isolation structure within a boundaryregion of the substrate disposed between the logic region and theembedded memory region, the first isolation structure has an uppersurface facing away from the substrate; subsequently increasing a heightof a part of the first isolation structure by forming a protrusionextending outward from the upper surface, the protrusion includes asecond dielectric confined directly above the first dielectric; andforming a logic wall over the protrusion, the logic wall surrounds theembedded memory region and has a height greater than heights of theplurality of memory devices. In some embodiments, the logic wall isformed concurrently with the plurality of transistor devices.

In yet other embodiments, the present disclosure relates to anintegrated chip. The integrated chip includes a logic region having aplurality of transistor devices within a substrate; an embedded memoryregion having a plurality of non-volatile memory (NVM) devices withinthe substrate; and a boundary region separating the embedded memoryregion from the logic region, the boundary region includes a logic wallarranged over the substrate and continuously extending as a firstunbroken structure around the embedded memory region, and the logic wallhas a first height that is greater than heights of the plurality of NVMdevices. In some embodiments, the integrated chip further includes amemory wall arranged between the logic wall and the plurality of NVMdevices, and continuously extending as a second unbroken structurearound the embedded memory region. In some embodiments, the integratedchip further includes a first isolation structure having a firstdielectric material disposed within the substrate in the boundaryregion, the logic wall is arranged over a first upper surface of theisolation structure and the memory wall is arranged over a second uppersurface of the isolation structure. In some embodiments, the logic wallincludes a logic wall core comprising a conductive material; and adielectric structure separating the logic wall core from the firstisolation structure. In some embodiments, the integrated chip furtherincludes a second isolation structure having a second dielectricmaterial disposed within the substrate in the boundary region betweenthe first isolation structure and the logic region; and a plurality ofdummy gate stacks arranged over the second isolation structure. In someembodiments, the plurality of dummy gate stacks have a second heightthat is less than the first height of the logic wall.

In yet other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming a plurality ofmemory device structures over a substrate; forming a first isolationstructure within a recess in the substrate; increasing a height of apart of the first isolation structure; forming a plurality of transistorgate stacks over the substrate, the first isolation structure is betweenthe plurality of transistor gate stacks and the plurality of memorydevice structures; and forming a logic wall over the first isolationstructure concurrent with formation of the plurality of transistor gatestacks, the logic wall surrounds the plurality of memory devicestructures. In some embodiments, the transistor gate stacks include ametal gate electrode including one or more gate metals; and the logicwall includes polysilicon.

In yet other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming a firstisolation structure within a recess in a substrate; forming a pluralityof memory device structures within the substrate; increasing a height ofa part of the first isolation structure to provide the first isolationstructure with a first upper surface and a second upper surface that isbelow the first upper surface; forming a plurality of transistor gatestacks separated from the plurality of memory device structures by thefirst isolation structure, the plurality of transistor gate stacksinclude a sacrificial gate electrode layer; forming a logic wall overthe first upper surface concurrent with formation of the plurality oftransistor gate stacks, the logic wall surrounds the plurality of memorydevice structures; and performing a replacement metal gate process toreplace the sacrificial gate electrode layer within the plurality oftransistor gate stacks (808 a-808 b) with one or more gate metals. Insome embodiments, the method further includes forming a memory wall overthe second upper surface, the memory wall surrounds the plurality ofmemory devices and is surrounded by the logic wall.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of forming an integrated chip,comprising: forming a first isolation structure within a boundary regionof a substrate that is disposed between a logic region of the substrateand an embedded memory region of the substrate, wherein the firstisolation structure is formed within a recess in the substrate; forminga plurality of memory devices within the embedded memory region; forminga plurality of transistor devices within the logic region; and forming alogic wall over the first isolation structure, wherein the logic wallsurrounds the embedded memory region and has a first height that isgreater than heights of the plurality of memory devices.
 2. The methodof claim 1, wherein the logic wall is formed concurrently with theplurality of transistor devices.
 3. The method of claim 1, wherein theplurality of transistor devices respectively comprise a metal gateelectrode having one or more gate metals; and wherein the logic wallcomprises polysilicon.
 4. The method of claim 1, further comprising:forming a second isolation structure within the substrate, wherein thefirst isolation structure extends to within the substrate to a greaterdepth than the second isolation structure; and forming one or more dummygate structures vertically over the second isolation structure andlaterally between the first isolation structure and the plurality oftransistor devices.
 5. The method of claim 1, further comprising:increasing a height of a part of the first isolation structure to definea protrusion extending outward from an upper surface of the firstisolation structure.
 6. The method of claim 5, wherein the height of thepart of the first isolation structure is increased using a thermaloxidation process.
 7. The method of claim 1, further comprising: forminga memory wall over the first isolation structure; forming a maskinglayer over the substrate and over the memory wall; and increasing aheight of a part of the first isolation structure in an area of thefirst isolation structure that is exposed by the masking layer.
 8. Themethod of claim 7, further comprising: forming the logic wall over thefirst isolation structure with the masking layer in place over thememory wall.
 9. A method of forming an integrated chip, comprising:forming a first isolation structure within a recess in a substrate;forming a plurality of memory device structures over the substrate;forming a plurality of transistor gate stacks over the substrate,wherein the first isolation structure is between the plurality oftransistor gate stacks and the plurality of memory device structures;and forming a logic wall over the first isolation structure concurrentwith formation of the plurality of transistor gate stacks, wherein thelogic wall has an uppermost surface that is above uppermost surfaces ofthe plurality of transistor gate stacks.
 10. The method of claim 9,further comprising: increasing a height of a part of the first isolationstructure after forming the plurality of memory device structures overthe substrate.
 11. The method of claim 10, wherein the height of thepart of the first isolation structure is increased using a hightemperature oxide process.
 12. The method of claim 9, furthercomprising: forming an etch stop layer over the logic wall; forming aninter-layer dielectric (ILD) layer over the etch stop layer; andperforming a planarization process to remove the etch stop layer and theILD layer from over the logic wall.
 13. The method of claim 9, furthercomprising: forming a memory wall over the first isolation structureconcurrent to forming the plurality of memory device structures, whereinthe memory wall is laterally separated from the logic wall by a non-zerodistance.
 14. The method of claim 9, wherein the logic wall comprises: apolysilicon core; and one or more sidewall spacers laterally surroundingthe polysilicon core.
 15. The method of claim 9, wherein the logic wallsurrounds the plurality of memory device structures.
 16. A method offorming an integrated chip, comprising: forming a first isolationstructure within a recess in a substrate; forming a plurality of memorydevice structures within the substrate; increasing a height of a part ofthe first isolation structure to provide the first isolation structurewith a first upper surface and a second upper surface that is below thefirst upper surface; forming a plurality of transistor gate stacks overthe substrate, wherein the plurality of transistor gate stacks areseparated from the plurality of memory device structures by the firstisolation structure; and forming a logic wall over the first uppersurface of the first isolation structure.
 17. The method of claim 16,further comprising: forming the plurality of transistor gate stacks tocomprise a sacrificial gate electrode layer concurrent to forming thelogic wall; and performing a replacement metal gate process to replacethe sacrificial gate electrode layer within the plurality of transistorgate stacks with one or more gate metals.
 18. The method of claim 16,further comprising: performing a thermal oxidation process to increasethe height of the part of the first isolation structure.
 19. The methodof claim 16, further comprising: forming a second isolation structurewithin the substrate; and forming one or more dummy gate structures overthe second isolation structure and between the first isolation structureand the plurality of transistor gate stacks.
 20. The method of claim 19,wherein the one or more dummy gate structures are formed concurrent withthe logic wall.